THE SKELETON AND TEETH 143
backwards; and the lower end of the fibula is relatively stronger than in Man.
Between the two bones there is a wider space than in Man. In the Gorilla the upper end of the tibia is very similar to that in Man, but the spine and anterior tnberosity are slightly larger. The internal tuberoshy is also better marked, but the interosseous and subcutaneous borders are weaker. The articular surface of the lower end is shallower than in Man, and the surface for articulation with the well-developed lower end of the fibula is not concave. The latter bone has a flatter distal surface than in Man, and its two articular facets are well marked.
Bones of the Ankle and Foot.—The bones of the foot in the Gorilla are more for supporting purposes than in the Orang and Chimpanzee, in which they are more adapted for grasping and climbing; so they differ to a greater or less extent from those in Man. In the Gibbons the foot approaches that of Man more closely than does that of the Chimpanzee or Orang. The os calcis is very strong, and the hallux is relatively longer than in the other Apes. In the Chimpanzee the os calcis is relatively weak compared with that in Man, and it is transversely compressed. It projects farther back than in the Orang. The scaphoid projects farther down into the sole than in Man, and the internal cuneiform is rotated in the same way; the result is that the hallux is attached to the tarsus in a manner which allows it to be easily opposed towards the other digits. The whole foot is narrower than in Man, and it is also longer. And Vrolik (217) points out that these deviations from the human conditions are present, but to a still greater degree, in the Orang; and he